1. Field of the Invention
The present invention relates to a portable polishing unit for dental instruments such as scalers for removing dental calculi, which can accurately and rapidly polish worn-out edge surfaces of the working means thereof.
2. Statement of the Prior Art
In most cases, working means having an edge surface or surfaces on one side or both sides are attached to dental instruments for filling and forming dental composite resins or cements in and on proximal surfaces of teeth or tooth cavities. Polishing is required for such dental instruments having edged working means, since their edge surfaces wear away be use.
Hitherto, polishing for such edged working means of the dental instruments has been carried out by applying them to a plane portion of a grindstone of a rectangular parallelpipal shape at a predetermined angle and moving the grindstone or the instruments.
In most cases, however, the edged working means of the dental instruments have their edge surfaces curved or one of their edge surface arched. Thus, considerable skill, labor and time are required to polish such curved edge surface or arched edge surface with the grindstone of a rectangular parallelpipal shape, since all of the polishing surfaces of such grindstones are planar.
In order to eliminate the disadvantage of the conventional method for polishing the edge surfaces of the working means of dental instruments, a polishing device including a grindstone driven and rotated by a motor has been proposed in, for instance, Japanese Utility Model Publication of the application No. 53-1672. Even with this device, it is not possible to effect polishing in a state where the edge surfaces of the working means of dental instruments are precisely and stably located on the polishing face of the rotating grindstone. As a result, one problem arises that the edge surfaces of the working means of dental instruments are so excessively polished that their service life shortens. Another problem also arises that the edge surfaces of the working means of dental instruments are excessively polished by the rotating grindstone so that burrs occur thereon.